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Founder & Editor-in-Chief VS Grenier's article, Dinosaur Tracks in My Backyard, won 7th place in the Preditors & Editors Reader Poll 2008 for Best Nonfiction. Dinosaur Tracks in My Backyard!
By: VS Grenier
Have you ever seen a dinosaur in your backyard? How about dinosaur tracks? What if I told you someone in my town did find dinosaur tracks . . . in their backyard?
 On my visit to the St. George Dinosaur Discovery Site at Johnson Farm, Anneli M. Segura, the site coordinator, shared the story of how this site was discovered. “In 2000, Dr. Sheldon Johnson (an 81 year old retired eye doctor) was leveling a hill in his yard when a huge rock flipped from his backhoe. He saw a foot sticking out of the rock and he immediately thought he had unearthed a whole dinosaur. He quickly contacted the local college. They contacted the Utah Geological Survey, who quickly came over. They started unearthing hundreds of tracks and other trace fossils.
“Dr. Johnson and his wife, LaVerna, immediately saw the importance of preserving what he had found. They began efforts to build a museum directly over the thousands of tracks and other fossils that were found here.”
The Dinosaur Discovery Site at Johnson Farm is one of twelve dinosaur sites in Utah. What makes the Johnson Farm site such a wonderful discovery is the exceptionally well-preserved dinosaur tracks. They not only have common impression tracks, but also a large number of spectacular natural casts. These casts show that dinosaurs came into the area to eat and drink, leaving footprints in the mud of a prehistoric lake.
To a novice, some of the natural casts look like nothing more than large clumps of mud stuck on rocks. But to a paleontologist, the casts are an amazing snapshot into the past.
Dr. Andrew R.C. Milner, St. George City Paleontologist and Johnson Farm Site Curator, said, “To the trained eye, the ridges (which are natural casts of swim tracks) show amazing preservations such as claw scratches, skin impressions, and scale scratch lines. Claw tips can be clearly seen at the ends of most of the ridges which are arranged in sets of three. Because the claw tips are pointing backward, scientists can actually determine which represent the three toes clearly seen on a majority of dinosaur tracks.”
The discovery of the St. George Dinosaur site helped confirm the theory of a prehistoric ocean and lake covering the Utah, Nevada, Arizona, Wyoming, Colorado, and New Mexico areas. Knowing where this ocean and lake existed helps paleontologists understand where dinosaurs lived, how the area looked at the time, and climatic changes of the past.
In the Utah areas of the Beaver Dam Mountains and Virgin Gorge, paleontologists study the prehistoric ocean that existed 510 to 235 million years ago. One great example is the 250 million-year-old Kaibab Limestone, which is exposed around the Bloomington area of Southern Utah. The Kaibab Limestone contains fossils, but only of invertebrate fish that lived in this ocean. What does this tell a paleontologist? That the Johnson Farm Site was produced along the western edge of the large prehistoric fresh water lake called Lake Dixie.
Lake Dixie formed during the end of the Triassic Period around 215-200 million years ago. The prehistoric ocean retreated, leaving a pocket of fresh water and river systems crisscrossing what is today the St. George area. “This means events in the past will occur again. Their impacts on the biological world through time certainly provide important clues as to our Earth’s future. It is extremely rare to have a [dinosaur track] site showing so many important details that it can be reconstructed so clearly,” said Dr. Milner.
The Johnson Farm is the only site where dinosaur tracks and natural casts have been found along with trace fossils. During digs, paleontologists have discovered hundreds of these fossils such as pond scum, fish, plants, rare dinosaur remains, invertebrate’s traces, snails, crustaceans, and important sedimentary structures.
 But what dinosaurs made these tracks? One large three toed track is the Eubrontes, which was made by a Dilophosaurus-like dinosaur. This dinosaur was believed to be 15 to 20 feet long, stood about 6 to 7 feet in height, and weighed somewhere between 700 to 1,000 ponds. However, some tracks are still being identified by researchers. To date only 25 track casts have been identified.
Next time you’re digging up the backyard, look closely at the rocks you find. Who knows, you might be the next one to discover . . . Dinosaur Tracks!
****************************************************************************************************************************** Word Meaning: Utah Geological Survey—a division of the Utah Department of Natural Resources. They provide scientific information about Utah's environment, resources, and hazards. Trace fossils—indirect evidence of life in the past such as footprints, swim tracks, burrows, borings, and feces left behind by animals. Impression tracks—these are formed by animals kicking their feet in a swimming motion and the toes strike the soft, muddy, clay-rich bottom along the shores of prehistoric lakes or oceans. Natural casts—this happens when sand fills an impression track and the muddy shore dries out. Over time, the sand turns into sandstone and takes the form of a footprint or swim track. Paleontologist—a scientist who studies paleontology, learning about the forms of life that existed in former geologic periods, chiefly by studying fossils. Climatic changes—this refers to the variation in the Earth's global climate or regional climates over time. Triassic Period—a time when the Earth was one big land mass starting to break apart and the climate of the Earth began to change. Also known as a time of change or transition. What to learn more about the Dinosaur Discovery Site? Visit their website at: The St. George Dinosaur Discovery Site at Johnson Farm in St. George, Utah. http://www.dinotrax.com Want to know if you have Dinosaurs in your backyard? Here is a small list of Dinosaur Sites and Museums:
Photograph Copyright © 2008 VS Grenier
Copyright © 2008 by VS Grenier |
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